Do you just draw art of your pet and it covers the original art, or does it have to fill the same space (if that makes sense), or are there special requirements for it?

Click here for instructions and rules.

If you go to the overlay page you have to click the "upload new" button to get to the instructions (a little backward and confusing). That leads to the page I linked above, where you do the actual submitting.

your image has to be 200px by 200px, and will fully replace the image of whichever pet you assign it to. all other rules and requirements are explained on the page linked.